by Emily Goebel, MD FRCPC
June 1, 2022
Extramammary Paget disease of the vulva is a type of vulvar cancer. The tumour starts in the skin on the surface of the vulva. It is considered a type of adenocarcinoma. Paget disease rarely spreads to lymph nodes or other parts of the body. It can, however, re-grow in the same location after surgery.
The diagnosis of extramammary Paget disease of the vulva is usually made after a small sample of tissue is removed in a procedure called a biopsy. The entire tumour will usually be removed fully in a larger surgical procedure called an excision or vulvectomy.
The microscopic appearance of extramammary Paget disease in the vulva.
Your pathologist may perform a test called immunohistochemistry to confirm the diagnosis and to exclude other cancers that may look similar to extramammary Paget disease. The tumour cells will be positive or reactive for immunohistochemical markers such as CK7 and GCDFP-15 and negative or non-reactive for p63 and S100, which you may see included in your pathology report.
Extramammary Paget disease starts from cells normally found on the surface of the vulva called the epidermis. As the tumour grows, the cells usually stay in the epidermis. However, over time, tumour cells can spread into the layers of tissue below the epidermis, specifically the dermis or subcutaneous tissue. Pathologists use the term invasion to the spread of tumour cells into these layers of tissue. Tumours that show deep invasion into the dermis or subcutaneous tissue are more likely to spread to lymph nodes or other parts of the body.
A margin is any tissue that has to be cut by the surgeon in order to remove the tumour from your body. A negative margin means that no cancer cells were seen at the cut edge of the tissue. In contrast, a positive margin means that cancer cells were seen at the cut edge of the tissue. A positive margin increases the risk that the tumour will grow back in that location.